Computing devices have made significant contributions toward the advancement of modern society and are utilized in a number of applications to achieve advantageous results. Numerous devices, such as digital cameras, computers, game consoles, video equipment, hand-held computing devices, audio devices, and telephones, have facilitated increased productivity and reduced costs in communicating and analyzing data in most areas of entertainment, education, business and science. The digital camera, for example, has become popular for personal use and for use in business.
FIG. 1 shows an exemplary digital camera. The digital camera 100 typically includes one or more lenses 110, one or more filters 120, one or more image sensor arrays 130, an analog-to-digital converter (ADC) 140, a digital signal processor (DSP) 150 and one or more computing device readable media 150. The image sensor 130 includes a two-dimension array of hundreds, thousand, millions or more of imaging pixels, which each convert light (e.g. photons) into electrons. The image sensor 130 may be a charge coupled device (CCD), complementary metal oxide semiconductor (CMOS) device, or the like. The filter 120 may be a Bayer filter that generates a mosaic if monochrome pixels. The mosaic of monochrome pixels are typically arranged in a pattern of red, green and blue pixels.
In an exemplary implementation, the digital camera 100 may include a lens 110 to focus light to pass through the Bayer filter 120 and onto the image sensor 130. The photons passing through each monochrome pixel of the Bayer filter 120 are sensed by a corresponding pixel sensor in the image sensor 130. The analog-to-digital converter (ADC) 140 converts the intensity of photons sensed by the pixel sensor array into corresponding digital pixel data. The raw pixel data is processed by the DSP 150 using a demosaic algorithm to produce final interpolated pixel data. The final interpolated pixel data is typically stored in one or more of the computing device readable media 160. One or more of the computing device readable media 160 may also store the raw pixel data.
Referring now to FIG. 2, an exemplary Bayer filter is shown. The Bayer filter pattern alternates rows of red and green filters 210, 220 with rows of blue and green filters 230, 240. The Bayer filter interleaves the red, green and blue color filters so that (1) each pixel only senses one color, and (2) in any 2×2 pixel cluster on the sensory plane, there are always two pixels sensing green information, one pixel for red, and one for blue. A demosaic algorithm interpolates the other two color components for each pixel from the surrounding raw pixel data. For example, if a given pixel generates a red signal, the demosaic algorithm interpolates a green and a blue color signal from the surrounding raw pixel data.
The Bayer filter/image sensor is subject to color artifacts. A color artifact happens when a scene contains a high frequency pattern that is beyond the Bayer array's Nyquist rate. Accordingly, there is a continuing need for improved imaging processing techniques to reduce color artifacts.